ucsd-progsys/liquidhaskell

Question about Dependent Sums

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#1,615 创建于 2020年2月14日

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errormsggood first issue

描述

Hi, I'm trying to represent a function that returns a dependent sum like below

{-@ measure isLeft :: Either a b -> Bool @-}
isLeft (Left _) = True
isLeft (Right _) = False

{-@ example :: x:Int -> {v : Either Int String | (isLeft v && x > 0) || (not (isLeft v) && x <= 0)} @-}
example x =
    if x <= 0 then Right "hello" else Left 1

but am running into issues with liquid. Am I representing this correctly? Even without generics, this still doesn't seem to work in the way I might expect.

贡献者指南

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documentation
议题类型
research
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4
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1-3 hours
活动状态议题当前的可参与程度：新鲜、活跃、陈旧、阻塞或等待维护者输入。
stale
清晰度议题是否清楚说明期望改动、验收标准和下一步。
mostly clear
前置要求
basic LiquidHaskell knowledgeHaskelldependent types
新手友好度1-100 的估计分数，表示该议题对首次贡献者的友好程度。
20
研究方向
The issue asks if the provided LiquidHaskell refinement for a dependent sum is correct. Investigate how LiquidHaskell handles dependent sums with measures and conditionals. Check the LiquidHaskell source and test suite for similar examples. If the syntax is correct but fails, it may be a bug; otherwise, provide the correct encoding.
Question about Dependent Sums · ucsd-progsys/liquidhaskell#1615 | Good First Issue